Take a fairly well-known miracle, the resurrection of Jesus. There is little or no evidence that it happened or that Jesus even existed. The course of the religion was influenced by people's belief in the event. Faith being the evidence of things not seen, it doesn't seem important for the miracle to be seen at all.
"Because you have seen Me, you have believed; blessed are those who have not seen and yet have believed." -John 20:29
Miracles have a few purposes. They are for edification, and they are the product of deep faith. We are asked to believe that God can do all things. Often times we don't believe that, or if we claim to, sometimes its just lip service. But Jesus also said that we have not because we ask not.
I would say that miracles are wonderful gifts on those He bestows upon. However, I could go the rest of my life without seeing one miracle and still have a deep relationship with the Father. At the same time, we shouldn't speak disparagingly about them either.
"A man can no more diminish God's glory by refusing to worship Him than a lunatic can put out the sun by scribbling the word, 'darkness' on the walls of his cell." -C.S. Lewis
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